Multiple choice

If the diametre of a sphere is decreased by 25%, its curved surface area will be decreased by-

  1. 43.25%

  2. 43.50%

  3. 43.75%

  4. 44.25%
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Surface area of sphere = 4πr². If diameter decreases by 25%, radius decreases by 25%, so new radius = 0.75r. New surface area = 4π(0.75r)² = 4π × 0.5625r² = 0.5625 × 4πr². Decrease = 1 - 0.5625 = 0.4375 = 43.75%.

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